Astro Boy set in a futuristic world wherein androids co-exist with humans.

Its focus is on the adventures of "Astro" , a powerful robot created by the head of the Ministry of Science, Doctor Tenma, to replace his son Tobio, who died in a car accident. Doctor Tenma built Astro in Tobio's image and treated him as lovingly as if he were the real Tobio, but soon realized that the little android could not fill the void of his lost son, especially given that Astro could not grow older or express human aesthetics . Tenma rejected Astro and sold him to a cruel circus owner, Hamegg.

After some time, Professor Ochanomizu, the new head of the Ministry of Science, noticed Astro performing in the circus and convinced Hamegg to turn Astro over to him. He then took Astro as his own and treated him gently and warmly, becoming his legal guardian. He soon realized that Astro was gifted with superior powers and skills, as well as the ability to experience human emotions.